Vegetable oil-based pressure sensitive adhesives

ABSTRACT

A pressure sensitive adhesive construct comprising:
         (a) a backing substrate; and   (b) a pressure sensitive adhesive composition disposed on the backing substrate, wherein the pressure sensitive adhesive includes a product made from at least one epoxidized vegetable oil and at least one dibasic acid or anhydride, or a combination of a dibasic acid or anhydride and a monobasic acid or anhydride.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 13/701,782, filedDec. 3, 2012, which is the U.S. National Stage of InternationalApplication No. PCT/US2011/039450, filed Jun. 7, 2011, which waspublished in English under PCT Article 21(2), which in turn claimspriority to U.S. Provisional Application No. 61/352,691, filed Jun. 8,2010, and U.S. Provisional Application No. 61/394,726, filed Oct. 19,2010, which are incorporated herein in their entirety.

BACKGROUND

A pressure sensitive adhesive (PSA) (also known as “self adhesive” or“self stick adhesive”) is an adhesive which forms a bond at roomtemperature with a variety of dissimilar surfaces when light pressure isapplied. No solvent, heat or radiation is needed to activate theadhesive. It finds wide applications in pressure-sensitive tapes and/orfoils, general purpose labels, note pads, automobile trim, packaging,medical, and a wide variety of other products.

Nowadays, most commercially available PSAs are derived from rubber,acrylic, modified acrylic, and silicone-based formulations, which arepredominately made from petrochemical-based polymers. Given thatpetroleum and natural gas are depleting nonrenewable resources withnaturally limited supply and increasing cost, it is desirable to providePSA compositions that can be made from renewable natural materials. Inaddition, it is highly desirable that the manufacture and use of PSA donot generate environmental pollution.

Vegetable oils are one of the most abundant renewable materials.Approximately 20 billion pounds are produced annually in the UnitedStates. At present, less than 600 million pounds of soybean oil is usedin industrial application. Therefore, there is plenty of soybean oilavailable for new industrial uses.

Vegetable oil is mainly a mixture of triglycerides with varyingcomposition of long-chain saturated and unsaturated fatty acidsdepending on the plant, the crop, and the growing conditions. The doublebonds in unsaturated fatty acids may be converted into more reactiveoxirane moieties (the epoxy functional groups) by appropriate reactions.Epoxidized vegetable oils (EVOs) such as epoxidized soybean oil (ESO)are commercially available and are widely used in rubbers, plastics,resins, coatings, and various thermosetting composites.

The use of vegetable oils as starting materials for making PSAs hasnumerous advantages such as low cost, low toxicity, inherentbiodegradability, and fairly high purity. Three general approaches formaking PSAs from vegetable oils have been disclosed (see WO2008/144703). In the first approach, free-radically polymerizablefunctional groups such as acrylate or methacrylate groups are firstintroduced onto fatty acid, fatty esters or vegetable oils and thenpolymerized via a free radical polymerization method such as ultravioletradiation to form PSAs. The introduction of the functional groups istypically accomplished through the reaction between epoxidized fattyesters or epoxidized oils and acrylic acid/methacrylic acid. During thepolymerization, various acrylic or methacrylic monomers may be used toco-polymerize with acrylated fatty esters/fatty acids/oils. In thisapproach, petrochemical-based acrylate is still used. This approach isconsidered as an extension of traditional free radical polymerizationmethods of making petrochemical-based PSAs. In the second approach,fatty ester or vegetable oils are first epoxidized. The epoxidized fattyesters or epoxidized vegetable oils are then polymerized to form PSAsthrough cationically catalyzed ring-opening polymerization of the epoxyrings. Some other epoxy compounds may be copolymerized with epoxidizedfatty esters or epoxidized vegetable oils for improving the propertiesof PSAs. The third approach involves the direct polymerization ofcarbon-carbon double bonds on fatty acids, fatty esters or vegetableoils with other free-radically polymerizable compounds such as acrylateor methacrylate. Unlike those in drying oils such as Tung oil, mostcarbon-carbon double bonds in vegetable oils are not conjugated, thushaving relatively low reactivity during the free radical polymerization.In this third approach, fatty acids, fatty esters or vegetable oils haveto be modified to form conjugated double bonds before the free radicalpolymerization.

SUMMARY

Disclosed herein are pressure sensitive adhesive compositions, pressuresensitive adhesive constructs, methods for making pressure sensitiveadhesive compositions and methods for making pressure sensitive adhesiveconstructs.

One embodiment disclosed herein is a pressure sensitive adhesiveconstruct comprising:

(a) a backing substrate; and

(a) a pressure sensitive adhesive composition disposed on the backingsubstrate, wherein the pressure sensitive adhesive composition includesa product made from at least one epoxidized vegetable oil and at leastone dibasic acid or anhydride thereof, or a combination of a dibasicacid or anhydride thereof and a monobasic acid or anhydride thereof.

A further embodiment disclosed herein is a pressure sensitive adhesiveconstruct comprising:

(a) a backing substrate; and

(b) a pressure sensitive adhesive composition disposed on the backingsubstrate, wherein the pressure sensitive adhesive composition comprisesa polyester condensation product that includes an epoxidized vegetableoil component crosslinked with at least one dibasic acid or anhydridethereof, or a combination of a dibasic acid or anhydride thereof and amonobasic acid or anhydride thereof.

An additional embodiment disclosed herein is a method for making apressure sensitive adhesive construct comprising:

reacting at least one epoxidized vegetable oil with at least one dibasicacid or anhydride thereof, or a combination of a dibasic acid oranhydride thereof and a monobasic acid or anhydride thereof; and

forming on a backing substrate a pressure sensitive adhesive from theresulting reaction product.

Another embodiment disclosed herein is a method for making a pressuresensitive adhesive composition comprising:

(a) reacting at least one epoxidized vegetable oil with at least onemonobasic acid or anhydride thereof resulting in a modified epoxidizedvegetable oil; and

(b) reacting the modified epoxidized vegetable oil with at least onedibasic acid or anhydride thereof to produce a pressure sensitiveadhesive composition.

Also disclosed herein is a method for making a pressure sensitiveadhesive composition comprising:

reacting at least one epoxidized vegetable oil with at least one dibasicacid or anhydride thereof, or a combination of a dibasic acid oranhydride thereof and a monobasic acid or anhydride thereof to produce apressure sensitive adhesive composition, wherein the amount of dibasicacid or anhydride reacted with the epoxidized vegetable oil is in amolar ratio of dibasic acid carboxyl groups to epoxidized vegetable oilepoxy groups of from 3:1 to 1:3.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a combination of reactive extrusion and reactivecalendar for the preparation of PSA and PSA tapes as disclosed herein.

DETAILED DESCRIPTION

As used herein, the singular terms “a,” “an,” and “the” include pluralreferents unless context clearly indicates otherwise. Also, as usedherein, the term “comprises” means “includes.”

The term “aliphatic” is defined as including alkyl, alkenyl, alkynyl,halogenated alkyl and cycloalkyl groups as described above. A “loweraliphatic” group is a branched or unbranched aliphatic group having from1 to 10 carbon atoms.

The term “alkyl” refers to a branched or unbranched saturatedhydrocarbon group of 1 to 24 carbon atoms, such as methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl,octyl, decyl, tetradecyl, hexadecyl, eicosyl, tetracosyl and the like. A“lower alkyl” group is a saturated branched or unbranched hydrocarbonhaving from 1 to 10 carbon atoms. Preferred alkyl groups have 1 to 4carbon atoms. Alkyl groups may be “substituted alkyls” wherein one ormore hydrogen atoms are substituted with a substituent such as halogen,cycloalkyl, alkoxy, amino, hydroxyl, aryl, or carboxyl.

The term “aryl” refers to any carbon-based aromatic group including, butnot limited to, benzene, naphthalene, etc. The term “aryl” also includes“heteroaryl group,” which is defined as an aromatic group that has atleast one heteroatom incorporated within the ring of the aromatic group.Examples of heteroatoms include, but are not limited to, nitrogen,oxygen, sulfur, and phosphorous. The aryl group can be substituted withone or more groups including, but not limited to, alkyl, alkynyl,alkenyl, aryl, halide, nitro, amino, ester, ketone, aldehyde, hydroxy,carboxylic acid, or alkoxy, or the aryl group can be unsubstituted.

The term “cycloalkyl” refers to a non-aromatic carbon-based ringcomposed of at least three carbon atoms. Examples of cycloalkyl groupsinclude, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, and the like. The term “heterocycloalkyl group” is acycloalkyl group as defined above where at least one of the carbon atomsof the ring is substituted with a heteroatom such as, but not limitedto, nitrogen, oxygen, sulfur, or phosphorous.

Disclosed herein are new PSA compositions based on epoxidized vegetableoils (EVOs), and methods for the preparation of PSA formulations and PSAtapes and/or foils thereof. In general, an EVO is reacted with a dibasiccarboxylic acid or a combination of a monobasic carboxylic acid and adibasic carboxylic acid resulting in a PSA.

In one embodiment the PSA compositions include a polyester condensationproduct prepared at elevated temperatures of at least one EVO and atleast one dibasic acid or its anhydride derivative, and optionally atleast one monobasic acid or its anhydride derivative.

Certain embodiments of the PSA adhesive compositions disclosed hereinexhibit adhesiveness or tackiness at room temperature, are odorless, arenot made with organic solvents and/or toxic catalysts, consist of onlyrenewable materials, and/or are thermally curable.

The EVO may be made from a vegetable oil by converting at least aportion of vegetable oil's double bonds into more reactive oxiranemoieties. In particular embodiments, “EVO” generally refers to anyderivative of vegetable oils whose double bonds are fully or partlyepoxidized using any method, e.g. so called in situ performic acidprocess, which is the most widely applied process in industry. Herein,“vegetable oil” refers to a group of polyunsaturated triglycerides,which are composed of three fatty acids connected to a glycerolmolecule. Typically, the fatty acids are long chain (C12 to C24 or evenlonger) materials with multiple double bonds per chain. The vegetableoil can be palm oil, olive oil, canola oil, corn oil, cottonseed oil,soybean oil, linseed oil, rapeseed oil, castor oil, coconut oil, palmkernel oil, rice bran oil, safflower oil, sesame oil, sunflower oil, orother polyunsaturated vegetable oils (both naturally existing andgenetically modified), or mixtures thereof. In certain embodiments, morethan one EVO can be utilized in a single mixture if desired. EVOsgenerally have a functionality (including epoxy groups and possiblyhydroxyl groups thereof) well above two, which can result in polymerswith fairly high density of cross-linking when polymerized with dibasicacids, and therefore increase the modulus of the polymers and decreasetheir utility as PSAs. Therefore, in some embodiments, modifications ofthe composition are performed and/or reaction conditions are optimizedto obtain polyesters with appropriate density of cross-linking which areappropriate for PSA compositions. EVOs such as ESO and epoxidizedlinseed oil are also readily available from commercial suppliers such asSpectrum Chemical Mfg Corp, California, and Sigma-Aldrich Corp,Missouri.

The EVO may contain about 1.5 to about 6 epoxy groups (or even more) pertriglyceride. It is preferred that the EVO contain functionality (epoxynumber) of 2 to 5, more preferably 2.5 to 4.5. The epoxy functionalityof EVO can be controlled by epoxidizing less than all of the doublebonds of the starting vegetable oils. Or, according to particularembodiments, the EVOs with high functionality used in the present PSAcompositions may optionally be modified by reacting with at least onemonobasic acid or its anhydride derivatives (“modifier”), to lower theirepoxy functionality, and to reduce the rate and density of cross-linkingin the following polymerization with dibasic acids as described below inmore detail. The epoxy functionality of EVO (or modified EVO) determinesthe rate and density of cross-linking in the polymerizations of EVO anddibasic acids. The use and amount of a modifier and the choices of thepolymerization temperature and time are also among the factors thateventually determine the properties of the PSAs.

In particular embodiments, the dibasic acids used in the preparation ofthe PSAs may include any organic compounds that contain two carboxylicacid functional groups, and derivatives or analogs thereof. Thefollowing are also considered to be dibasic acids from the viewpoint ofpolycondensation chemistry: tribasic or higher H-functionality acids;and compounds that include two or more displaceable active hydrogenatoms per molecule but the hydrogen atoms are not part of a carboxylmoiety. More than one dibasic acid can be utilized in a single mixtureif desired. Dibasic acids can be aliphatic (linear, branch or cyclic)saturated carboxylic acids containing up to 30 carbon atoms, preferably3 to 22 carbon atoms, e.g., malonic acid, succinic acid, glutaric acid,adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, andbrassylic acid. Dibasic acids may also be aromatic acids and derivativesthereof, including without limitation, phthalic acid, isophthalic acidand terephthalic acid. Dibasic acid can also be produced from otherderivatives such as anhydrides. Specific examples include withoutlimitation succinic anhydride and phthalic anhydride. The dibasic acidsor anhydride derivatives are preferably derived from natural resources.In addition to the high energy-consuming traditional processes for theproduction of dibasic acids, alternative accesses to various dibasicacids from renewable feedstocks have been well reported (see, e.g,“Lipids as renewable resources: current state of chemical andbiotechnological conversion and diversification” by J. O. Metzger and U.Bornscheuer (Appl. Microbiol. Biotechnol. 2006)).

The monobasic acid which may form a part of the PSA compositions (e.g,as a “modifier” in certain embodiments) may be any of the organiccompounds that contain only one carboxyl group, e.g., free acids orderivatives thereof. More than one monobasic acid can be utilized in asingle mixture if desired. The monobasic acid can be an aliphatic(linear, branch or cyclic) saturated acid containing up to 36 carbonatoms, preferably 1 to 24 carbon atoms, e.g. formic acid, acetic acid,propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid,caprylic acid, pelargonic acid, capric acid, undecylic acid, lauricacid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid,margaric acid, stearic acid, nonadecylic acid, arachidic acid,heneicosylic acid, behenic acid, tricosylic acid, and lignoceric acid.The monobasic acid can also be aromatic acids and derivatives thereof,such as benzoic acid, naphthalene acid, and derivatives thereof. As isunderstood by those of ordinary skills in the art, monobasic acid canalso be produced from other derivatives such as anhydrides. Specificexamples include without limitation, acetic anhydride and propionicanhydride. The monobasic acid is preferably derived from naturalresources. For example, free fatty acid can be obtained by hydrolysis ofnatural fats and oils derived from plant or animal sources. In thisconnection, mixtures of free fatty acids or their esters may also beutilized as starting materials for the sake of cost effectiveness,although the saturated fatty acids are preferred.

In particular embodiments, in addition to the EVO, dibasic acid and/ormonobasic acid, the reaction mixture can also contain from about 0.05 to10.0, more particularly 0.1 to 10.0, parts by weight of a catalyst,preferably from about 0.1 to 2 parts by weight, based on the weight ofthe reactants, especially when the reaction is performed at lowtemperatures (e.g., <120° C.). The catalyst can reduce the cure time(e.g., a cure time of 3 to 6 minutes) of the reaction mixture. Severalcatalysts can be used to effectively catalyze the reaction betweencarboxyl groups and epoxy groups. These catalysts can be:

(1) amines, especially tertiary amines, —examples include but are notlimited to, triethylamine, trimethylamine, tri-n-pentylamine,trioctylamine, tridecylamine, tridodecylamine, trieicosylamine,docosyldioctylamine, triacontyldibutylamine, 2-ethylhexyldi-n-propylamine, isopropyl di-n-dodecylamine, isobutyldi-n-eicosylamine, 2-methyldocosyl di-(2-ethylhexyl) amine, triacontyldi-(2-butyldecyl) amine, n-octadecyl di-(n-butyl)amine, n-eicosyldi-(n-decyl)amine, n-triacontyl n-dodecylmethylamine,n-octyldimethylamine, n-decyldiethylamine n-dodecyldiethylamine,n-octadecyldimethylamine, n-eicosyl dimethylamine, n-octyln-dodecylmethylamine, n-decyl n-eicosylethylamine, n-octyldimethylamine,n-decyldimethylamine, n-dodecyldimethylamine, n-tetradecyldimethylamine,n-hexadecyldimethylamine, n-octadecyldimethylamine,n-eicosyldimethylamine, di-(n-octyl)methylamine,di-(n-decyl)methylamine, di-(n-dodecyl)methylamine,di-(n-tetradecyl)methylamine, di-(n-hexadecyl)methylamine,di-(n-octadecyl)methylamine, di-(n-eicosyl)methylamine, n-octyln-dodecylmethylamine, n-decyl n-octadecylmethylamine,dimethylbenzylamine, N,N-dimethylaniline, N,N-dimethylaniline,N-methyldiphenylamine, triphenylamine, N-methyl-N-dodecylanilinepyridine, 2-methylpyridine, triethanolamine, N-methylmorpholine,N-methylpiperidine, N-ethylpiperidine, N,N-dimethylpiperazine, 1-methylimidazole, 1-butylimidazole, 1,8-diazabicyclo[5.4.0]undec-7-ene,1,5-diazabicyclo[5.4.0]undec-5-ene, 1,5-diazabicyclo[4.3.0]non-5-ene,1,4-diazobicyclo[2.2.2]-octane, tetramethyl guanidine,N,N,N′,N′-tetramethyl-1,8-diaminonaphthalene, 2-phenyl-2-imidazoline,2-ethylimidazole, bis(2-ethylhexyl)amine, etc;

(2) metal salts or complexes (e.g., alkali metal salts of weak organicacid)—examples include but are not limited to, chromium (III)tris(acetylacetonate), chromium (III) 2-ethylhexanoate, chromium (III)hexanoate, chromium (III) octoate, chromium (III) stearate, chromium(III) naphthenate, 3,5-diisopropylsalicylato chromium (III) chelate,bis(3,5-diisopropylsalicylato)-monohydroxy chromium (III) chelate, zincacetate, zinc acetate dihydrate, zinc acetylacetonate, zinc octoate,zinc laurate, zinc salicylate, zinc glycinate, zinc gluconate, zincoleoylsarcosinoate, zinc naphthenate, zinc 2-ethylhexyl acid phosphatesalt, zinc butyl acid phosphate salt, zincdi-2-ethylhexyldithio-phosphate, zinc salt of dodecenyl succinate butylhalf ester, N-butylsalicylaldimio zinc (II) chelate, zinc isovalerate,zinc succinate, zinc dibutyl dithiocarbamate, stannous octoate, stannum(II) 2-ethylhexyl acid phosphate salt, titanium ethyl acetoacetatechelate, titanium acetoacetate chelate, titanium triethanolaminechelate, zirconium octoate, zirconium 6-methylhexanedione, zirconium(IV) trifluoroacetylacetone, 3,5-diisopropylsalicylato nickel (II)chelate, nickel acetylacetonate, N-butylsalicylaldimio nickel (II)chelate, 3,5-diisopropylsalicylato manganese (II) chelate, manganesenaphthenate, manganese naphthenate, magnesium 2,4-pentadionate, ironoctoate, ferric linoleate, iron (III) acetylacetonate, cobalt octoate,cobalt naphthenate, cobalt (III) acetylacetonate, N-butylsalicylaldimiocobalt (II) chelate, N-butylsalicylaldimio cobalt (III) chelate,3,5-diisopropylsalicylato cobalt (II) chelate, N-butylsalicylaldimiocopper (II) chelate, 3,5-diisopropylsalicylato copper (II) chelate,3,5-diisopropylsalicylato oxyvanadium (IV) chelate, aluminumacetylacetonate, aluminum lactate, dibutyltin dilaurate, dibutyltinoxide, butylchloro tin dihydroxide, cerium naphthenate, calcium octoate,bismuth octoate, lithium acetate, sodium acetate, potassium acetate,etc;

(3) quaternary ammonium compounds, —examples include but are not limitedto, tetrabutyl ammonium bromide, tetrabutyl ammonium iodide, tetrabutylammonium hydrogen sulphate, tetrabutyl ammonium fluoride, tetrabutylammonium chloride, tetraethyl ammonium bromide, tetraethylammoniumiodide, tetrapropylammonium bromide, tetrapropyl ammonium iodide,tetramethyl ammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, tetraoctyl ammonium bromide, benzyltriethyl ammoniumchloride, benzyltributyl ammonium chloride, benzyltrimethyl ammoniumchloride, benzyltrimethylammonium bromide, butyltriethyl ammoniumbromide, methyltrioctyl ammonium chloride, methyltricapryl ammoniumchloride, methyltributyl ammonium chloride, methyltributyl ammoniumbromide, methyltriethyl ammonium chloride, myristyltrimethyl ammoniumbromide, tetradecyltrimethyl ammonium bromide, cetyltrimethyl (orhexadecyltrimethyl) ammonium bromide, hexadectyltrimethyl ammoniumbromide, cetyltrimethylammonium chloride, hexadectyltrimethyl ammoniumchloride, lauryltrimethyl ammonium chloride, dodecyltrimethyl ammoniumchloride, phenyltrimethyl ammonium chloride, benzalkonium chloride,cetyldimethylbenzyl ammonium bromide, cetalkonium bromide,cetyldimethylbenzyl ammonium chloride, cetalkonium chloride, tetrabutylammonium perchlorate, tetrabutyl ammonium p-toluene sulfonate,tetraethyl ammonium p-toluene sulfonate, cetyltrimethyl ammoniump-toluene sulfonate, tetraethyl ammonium tosylate, tetrabutyl ammoniumtosylate, cetyltrimethyl ammonium tosylate, phenyltrimethyl ammoniumbromide, benzyltrimethyl ammonium hydroxide, tetrabutyl ammoniumhydroxide, tetramethyl ammonium hydroxide, etc;

(4) quaternary phosphonium compounds, —examples include but are notlimited to, tetrabutyl phosphonium bromide, ethyltriphenyl phosphoniumiodide, ethyltriphenyl phosphonium bromide, ethyltriphenyl phosphoniumiodide, butyltriphenyl phosphonium bromide, benzyltriphenyl phosphoniumchloride, methyltriphenyl phosphonium bromide, methyltriphenylphosphonium iodide, tetraphenyl phosphonium bromide, triphenylphosphonium bromide, methyltriphenyl phosphonium chloride, butyltriphenyl phosphonium chloride, (methoxy methyl)triphenyl phosphoniumchloride, etc;

(5) phosphines, such as triphenylphosphine, etc;

(6) alkali metal hydroxide, e.g. potassium hydroxide, sodium hydroxide,etc.

The catalyst may be added at any point during the prepolymerization fromthe initial charge until the coating of the reaction mixtures. Incertain embodiments, it is important that the catalyst be added when thecatalyst can be homogeneously distributed.

The PSA compositions may also include additives and fillers. Fillers mayeither originally occur in the starting materials such as esters offatty acids, or be included on purpose. Additives such as tackifiers,colored pigments, opacifiers, processing oil plasticizers, solvents andother constituents known to the tape art may be incorporated in thePSAs.

In certain embodiment, the polyester condensation product disclosedherein is the majority component of the pressure sensitive adhesivecomposition meaning the pressure sensitive adhesive composition includesat least about 50, particularly at least about 70, more particularly atleast about 80, and most particularly at least about 90, weight percentof the polyester condensation product based on the total weight of thepressure sensitive adhesive composition.

The reaction (e.g., polymerization) of EVO with dibasic acid andoptionally monobasic acid may be accomplished by heating a reactionmixture of EVO and dibasic acid or its anhydride derivative, or acombination of dibasic acid or its anhydride derivative and a monobasicacid or its anhydride derivative, under controlled conditions(especially reaction temperature and time), to a degree thatcross-linking does not obviously occur, and the viscosity of theintermediate reaction mixture is appropriate to allow blade-coating. Ifdesired, the reaction is preferably carried out under an inertatmosphere free from oxygen, e.g. under nitrogen, since the esters areeasily oxidized at high temperature to give dark-colored products. Thepolymerization compositions can be considered as a two-part system inwhich the EVO component (either unmodified or modified with a monobasicacid) comprises one part (component a) and the at least one dibasic acid(and optionally at least one monobasic acid) comprises the second part(component b). The two parts can be mixed together in three methods: (1)the two parts are mixed together at room temperature prior to heating;(2) component a in melt or liquid state is mixed together with componentb in solid state at room temperature, prior to heating together; (3)both component a and b are in melt or liquid state, prior to mixing andheating.

According to some particular embodiments, the novel EVO-based PSAcompositions may be prepared by heating the reaction mixture at atemperature suitably in the range from 80 to 300° C. for 1 to 20minutes, preferably from 100 to 220° C. for 3 to 10 minutes, and moreparticularly from 130 to 180° C. for 4 to 6 minutes. The compositionsmay have an open time of up to about 5 or 25 minutes, depending on thenature of the dibasic acid, the functionality of EVO, mixing methods,reaction temperature, and the nature and amount of catalysts (asdescribed above). As used herein, “open time” denotes the time frommixing of the two parts to the time at which cross-linking takes placeto a point that the mixed composition can no longer be applied.Generally, the higher the reaction temperature, the shorter the opentime. At lower temperature, the carboxylic acid groups are mainlyconsumed by epoxy groups. But at higher temperature, both epoxy groupsand hydroxyl groups derived from carboxyl-epoxy reaction may react withcarboxylic acid groups. As the reaction proceeds further, the carboxylicacid-hydroxyl esterification reaction dominates the reaction, with theresult that the density of cross-linking increases and the mixedcomposition becomes more difficult for coating and less appropriate forPSAs. The reaction can be controlled to generate coatings with low glasstransition temperature, sufficient cohesive strength, and good initialtack and adhesive powder which are appropriate for PSA.

In typical EVO-based PSA compositions disclosed herein, dibasic acid (oran anhydride thereof) can be used in molar ratios of carboxyl groups toEVO epoxy groups (or modified EVO) of from about 3:1 to about 1:3.However, excess carboxyl groups are preferably desired in the reactionmixture, so as to help control the rate and density of cross-linking andpromote the adhesive power of the final polyester products. Moreparticularly, the amount of dibasic acid used to make the PSAcompositions is preferably such as to provide a 5 to 80 mol % excess ofcarboxyl groups over that required to esterify all the epoxy groupspresent in the reaction mixture.

In certain embodiments, an initial or first-stage polymerization isaccomplished by heating the reaction mixture only to the extent thatcross-linking does not obviously occur, and the viscosity of thefirst-stage reaction mixture is sufficiently low to allow blade-coatingof the reaction mixture onto PSA backing materials or release liners(e.g., siliconized release liners). The PSA backing materials can bepaper, cellophane, plastic film, cloth, tape or metal foils.

The resulting prepolymer coatings on the backings are then heated suchas in an air-circulating oven so that appropriate cross-linking of thepolyesters can take place to give a “dry” adhesive layer of sufficientcohesion strength, good initial tack and adhesive power that areappropriate for PSA applications.

According to particular embodiments, the homogenous mixtures can beblade-coated within the open time on PSA backing substrates (such asKraft paper and PET film) or siliconized release liners with a glass barimmediately after heating of the mixed compositions, with the resultthat a thin, uniform layer of the mixed compositions is produced on thebacking or liner at a coating level of about 2 to about 10 mg/cm². Itshould be noted herein that, the “monomer” reaction mixtures (EVOs anddibasic acids) per se are generally of low viscosity, and may be too lowin fact to be handled conveniently. In order to increase their viscosityto a more desirable level, the “monomer” reaction mixtures are partiallypolymerized prior to coating to a desirable degree such that a fairlyhigh conversion of the dibasic acid is reached but cross-linking doesnot obviously occur, thus forming a clear “syrup” of appropriateviscosity.

According to some particular embodiments, the resulting adhesivecoatings on the PSA backings are then subjected to heat such as in anair-circulating oven maintained at 100-300° C. for 8 to 100 minutes(more particularly 10 to 100 minutes), preferably at 120-250° C. for 30seconds to 80 minutes, and more particularly at 150-200° C. for 1 to 60minutes, so that appropriate cross-linking of the polyesters can takeplace to give a “dry” adhesive layer of sufficient cohesion strength,good initial tack and adhesive power that are appropriate for PSAs.Generally, the higher the reaction temperature the shorter the durationof heating is needed to accomplish the polymerization to an idealdegree. However, before choosing the oven temperature, the heatstability of the PSA backing or siliconized release liners should beconsidered.

Although not bound by any theory, it is assumed that, due to the actionof heat, the reactive groups (carboxylic acid groups, and epoxy groupsand/or hydroxyl groups) which are still present in the pre-polymers onthe PSA backing, are activated to such an extent that they are capableof further polymerization and cross-linking. For PSA applications,cross-linking is desirable, particularly where it is desired to increasethe cohesive strength of the adhesive without unduly affecting itscompliance. However, too high density of cross-linking can bedeleterious to the PSA properties, with a severe loss of compliance asreflected in the peel test. Therefore, the reaction temperature and timeat this stage may be finely tuned for appropriate cross-linking of thePSA systems.

Also disclosed herein are new PSA compositions based on modified EVOs,and methods for the preparation of said PSA formulations and PSA tapesand/or foils thereof. In this embodiment, the PSA compositions include apolyester condensation product prepared at elevated temperatures ofmodified EVO and at least one dibasic acid or its anhydride derivative,wherein the modified EVO was made by reacting at least one EVO and atleast one monobasic acid or its anhydride derivative at elevatedtemperatures. It should be noted herein that, such modification at thesame time increases the hydrophilicity of EVO due to introduction ofhydroxyl groups, which facilitates the reaction between EVO and dibasicacids, and improves coating “wet-out” of the reaction mixture to tapebackings such as paper.

The novel EVO-based PSAs may be prepared by mixing (by any mixingmethods described above) and heating modified EVO and at least onedibasic acid or its anhydride derivative, or a combination of dibasicacid or its anhydride derivative and a monobasic acid or its anhydridederivative. Modified EVO is previously prepared by reacting EVO with atleast one monobasic acid or its anhydride derivatives, and catalysts (asdescribed above) if needed, at a temperature suitably in the range from80 to 300° C. for 10 seconds to 300 minutes, preferably from 100 to 220°C. for 30 seconds to 200 minutes, more particularly from 120 to 180° C.for 1 to 120 minutes. Generally, at this stage of modification of EVO,no cross-linking reaction occurs, regardless of the reaction temperatureand reaction time. The higher the reaction temperature, the shorter theduration of heating needed to accomplish the modification. At a lowertemperature, the carboxylic acid groups are mainly consumed by epoxygroups, but at higher temperature, hydroxyl groups derived fromcarboxylic acid-epoxy reaction may react with carboxylic acid groups.According to particular embodiments, the amount of monobasic acid usedin the present PSA compositions to react with EVO is preferably such asto leave about 1.5 to about 6 moles, more preferably about 2 to about 5moles, more particularly about 2.5 to about 4.5 moles of epoxy groups,in one mole of modified EVO.

The modified EVO so formed is then further mixed (by any mixing methodsdescribed above) and reacted with at least one dibasic acid or itsanhydride derivative, or a combination of dibasic acid or its anhydridederivative and a monobasic acid or its anhydride derivative, andcatalysts (as described above) if needed, at a temperature suitably inthe range from 80 to 300° C. for 10 seconds to 50 minutes, preferablyfrom 100 to 220° C. for 30 seconds to 30 minutes, and more particularlyfrom 130 to 180° C. for 1 to 20 minutes. The mixed compositions may havean open time of up to about 10 or 60 minutes, depending on the nature ofdibasic acid, functionality of the modified EVO, mixing method, reactiontemperature, and the nature and amount of catalysts (as describedabove).

In another embodiment, the prepolymer coatings on the release liners arecovered with a sheet of backing material, resulting in a sandwichassembly which is then pressed (e.g., with a rubber roller) to achievesufficient wet-out of the adhesive onto the PSA backing. Subsequently,the release liner is removed from the sandwich assembly, with theadhesive transferring onto the PSA backing. The resulting adhesivecoatings on the backing are then heated such as in an air-circulatingoven so that appropriate cross-linking of the polyesters can take placeto give a dry adhesive layer of sufficient cohesion strength, goodinitial tack and adhesive power that are appropriate for PSA.Alternatively, the sandwich assembly as a whole may be heated tocrosslink the polyester and then the release liner may be removed.

It should be noted that, the coating layer on the backing substrateafter heating might not have a good appearance, with blotches of no orlittle adhesive on the PSA backing, probably due to retraction of theadhesive during polymerization and cross-linking. The novel processdescribed above was developed to address this issue. As described above,the reaction mixture immediately after the pre-polymerization isinitially blade-coated on the siliconized face of siliconized releaseliners. The resulting adhesive coatings on the siliconized releaseliners are then covered with a sheet of PSA backing material, resultingin the sandwich assembly.

In still another embodiment, the preparation of a PSA composition andPSA tapes comprising the composition could be performed with the aid oftwo siliconized release liners with different adhesion-repellenceabilities to the adhesive composition. The reaction mixture immediatelyafter the pre-polymerization is initially blade-coated on thesiliconized face of a sheet of partially siliconized release liner. A“partially” siliconized release liner means that only a portion of therelease liner surface is covered by a silicone agent. A “fully”siliconized release liner means that substantially all of the releaseliner surface is covered by a silicone agent. The resulting adhesivecoating is then covered (the siliconized face inwardly) with a sheet offully siliconized release liner, resulting in a sandwich assembly whichis pressed (e.g., with a rubber roller) to achieve a good contactbetween the adhesive composition and the two liners. The sandwichassembly is then heated such as in an air-circulating oven so thatappropriate cross-linking of the polyesters can take place to give a dryadhesive layer of sufficient cohesion strength, good initial tack andadhesive power that are appropriate for PSA. Afterwards, the fullysiliconized release liner is quickly peeled off without taking away anyadhesive composition, after which a sheet of backing material such aspaper is immediately and carefully covered on the adhesive layer. Thenew “sandwich” is then pressed (e.g., with a rubber roller) to achievesufficient wet-out of the adhesive onto the paper backing in order toprovide adequate adhesion. After the sandwich assembly is cooled down,the partially siliconized release liner could be easily peeled off withthe adhesive composition completely transferring to the paper backing.In this embodiment, a first release liner such as, for example, thepartially siliconized release liner has an adhesion-repellence that isless than the adhesion-repellence of a second release liner such as, forexample, the fully siliconized release liner. In other words, the secondrelease liner can be more easily removed than the first release linermeaning that one release liner can be removed while the PSA compositionstill adheres to another release liner. The siliconized released linercan be optionally left for protection of the adhesive layers on thepaper backing. One of the advantages for this method is that lowmolecular weight starting materials for making the PSA composition donot penetrate the paper backing to give oily or dirty appearance of theresulting PSA tape.

According to particular embodiments, the present PSAs may be used tomanufacture many different types of PSA tapes. Thus, various flexibletape backings and liners may be used, including films (transparent andnon-transparent), plastics such as PET film or modified naturalsubstances such as cellophane, cloths, papers, non-woven fibrousconstructions, metal foils, metalized plastics foils, aligned filaments,etc.

The adhesive layers can be covered with papers or films which contain anadhesive-repellent layer, e.g. a separating layer consisting ofsilicone, for the protection of the adhesive layers on the PSA backings.The back side of the PSA films, tapes or foils can be coated with anadhesive-repellent coating (e.g. silicone coating) for facilitatingrolling off the PSA.

In still another embodiment, the preparation of the PSA and PSA tapesthereof as disclosed herein could be continuously performed using acombination of reactive extrusion and reactive calendaring, which isillustrated in FIG. 1. The reactive calendaring setup is a device thatincludes a series of rollers placed in an oven chamber. In oneembodiment, the rollers may be unheated and disposed of inside an ovenchamber at a preset temperature. In another embodiment, heated rollerscan be used and the whole calendaring setup does not need to be housedin an oven chamber.

As shown in FIG. 1, the prepolymerization is done continuously usingreactive extrusion in a mono- or twin-screw extruder. The hot prepolymerfrom the extruder is thereupon coated on a backing material (such asfilm or paper, et al) or a release liner, which is then laminated withanother release liner with different adhesion abilities to the adhesivecomposition, to give a sandwich assembly. Afterwards, the sandwichassembly is directed to heated calendar rollers or calendar rolls placedin an oven chamber at a preset temperature. The duration of the processcan be fine-tuned by adjusting the number and sizes of the rolls or thetravel distance of the assembly inside the oven chamber, so thatappropriate cross-linking of the polyesters can take place to give a dryadhesive layer of sufficient cohesion strength, good initial tack andadhesive power that are appropriate for PSA.

The vegetable oil-based PSA compositions and the method of making themare attractive from both the commercial and environmental perspectives.The advantages of these novel PSAs include without limitation:

(1) the starting materials can all be derived from naturally abundantand renewable resources, providing an alternative to petrochemical-basedPSAs;

(2) the products are biodegradable, thus alleviating environmentalpollution by used PSA-containing products;

(3) The composition is relatively simple and all ingredients areinexpensive, non-toxic and environmentally friendly. Additives that arecommonly used in many petrochemical-based PSAs such as tackifiers andwaxes may not be needed; and

(4) The processes of making the PSAs are short and simple, thusfacilitating a large scale production with low energy consumption. PSAscan be made without use of any organic solvent or hazardous expensivecatalysts. The whole processes are very environmentally friendly.

Example 1

This example describes the preparation of a PSA composition from ESO andadipic acid in a molar ratio of 1:1 oxirane group to carboxylic acidgroup and of PSA tapes comprising the composition. ESO (2.88 g,containing about 12.6 mmol of oxirane groups) and adipic acid (0.93 g,containing 12.7 mmol of carboxylic acid groups) were charged to a 50-mLround-bottom flask equipped with a heating mantle and a magneticstirring. The mixture was then heated at 180° C. with stirring. Afterthe mixture became clear and colorless, the heating was continued foranother three minutes at the same temperature to give a palegreenish-yellow, viscous “syrup”. The flask was then taken out of themantle, and the syrup was quickly blade-coated on a sheet of white kraftpaper with a glass rod at a coating level of about 8 mg/cm², to give athin, continuous, uniform layer of sticky, long-fiber-forming, “wet”coating. Subsequently, the paper coated with the adhesive layer wasplaced in an air-circulating oven maintained at 160° C. The heat causedthe cross-linking reaction of the coating composition. After 35 minutesin the oven, the coating became a clear, pale greenish-yellow, “dry”adhesive layer of sufficient cohesion. Some blotches of no or littleadhesive on the paper backing were noticeable probably due to retractionof the adhesive during polymerization and cross-linking. The finishedPSA tape thus obtained possessed good initial tack, formed ropystructure upon its removal from surfaces (e.g. metal, lacquer, glass,human skin) to which they are applied, and exhibited a good adhesivepower of about 1.6 lbf/inch on stainless steel (type 302). The 90° peeladhesion test method and conditions are described in Example 2; thesample tape was almost cleanly removed in the test, leaving only alittle adhesive residue on the panel.

Example 2

This example describes 90° peel adhesion test on stainless steel for thesample tapes. The measure of bond strength between an adhesive and asubstrate is defined as adhesion. Adhesion properties are typicallytested using the 90° peel adhesion test method by measuring the forcerequired to remove the pressure-sensitive material from a stainlesssteel, at a specified angle of 90°, and at a specified speed. Anexemplary 90° peel adhesion test of sample tapes on a stainless steeltest panel (type 302 stainless steel) consists of following steps:

-   -   (1) Clean the stainless steel test panel (2″ wide by 6″ long)        twice with Kimwipe napkin and acetone, and condition the panel        for about 15 minutes before applying the tape onto the panel.    -   (2) Randomly cut 5 strip specimens from each PSA-coated sample        sheet. The specimen size is 1″ wide by 6″ long.    -   (3) The specimen tape was laid onto the stainless steel panel        with the adhesive side down against the stainless steel test        panel, and pressed by two passes of a 4.5-pound hard rubber        roller in the direction parallel to the panel length, to achieve        sufficient wet-out onto the panel surface in order to provide        adequate adhesion.    -   (4) Let the pasted specimen tapes dwell for 20 minutes prior to        testing.    -   (5) Set up and calibrate the Instron 5582 testing machine in        accordance with the manufacture instructions. A five-pound load        cell was used, and the test speed was set at 12 inches per        minute.    -   (6) Place the tested specimen onto the upper jaw of the Instron        machine, and start testing. While the upper jaw was moving up,        the panel was passively moved in the horizontal direction along        the holder so that the specimen tape maintained a peel angle of        90° throughout the test.    -   (7) The force opposing that movement is automatically recorded        as average load in pounds.    -   (8) Repeat the above steps to test the rest of the specimens        (typically, five specimens were selected for each sample tape)        and average the results.

Example 3

This example describes the preparation of a PSA composition from ESO andadipic acid in a molar ratio of 1:1.35 oxirane groups to carboxylic acidgroups) and of PSA tapes comprising the composition. ESO (2.69 g,containing about 11.8 mmol of oxirane groups) and adipic acid (1.16 g,containing 15.9 mmol of carboxyl groups) were charged to a 50-mL,round-bottom flask equipped with a heating mantle and a magneticstirrer. The mixture was heated by the preheated mantle (180° C.) withstirring. After the mixture became clear and colorless, the heating wascontinued for another four minutes at the same temperature to give aclear, pale greenish-yellow, viscous “syrup”. The flask was then takenout of the mantle, and the syrup was quickly blade-coated on a sheet ofwhite kraft paper with a glass rod at a coating level of about 10mg/cm², to give a thin, continuous, uniform layer of sticky,long-fiber-forming, “wet” coating. Subsequently, the paper coated withthe adhesive layer was placed in an air-circulating oven maintained at160° C. The heat caused the cross-linking reaction of the coatingcomposition. After 45 minutes, the coating became a clear, palegreenish-yellow, shiny, “dry” adhesive layer of sufficient cohesionstrength, although some blotches of no or little adhesive on the paperbacking were noticeable probably due to retraction of the adhesiveduring polymerization and cross-linking. The finished PSA tape thusobtained possessed good initial tack, formed ropy structure upon removalof it from surfaces (e.g. metal, lacquer, glass, human skin) to whichthey are applied, and exhibited a good adhesive power of about 3.1lbf/inch on stainless steel (type 302). The 90° peel adhesion testmethod and conditions are described in Example 2; the sample tape wasalmost cleanly removed in the test, leaving only little adhesive residueon the panel.

Example 4

This example describes preparing a PSA composition from ESO and adipicacid in a molar ratio of 1:1.2 oxirane groups to carboxylic acid groupsand PSA tapes comprising the composition. ESO (2.56 g, containing about11.2 mmol of oxirane groups) and adipic acid (1.16 g, containing 13.7mmol of carboxylic acid groups) were charged to a 50-mL, round-bottomflask equipped with a heating mantle and magnetic stirring. The mixturewas heated by the preheated mantle (180° C.) with stirring. After themixture turned clear and colorless, the heating was continued foranother four minutes at the same temperature to give a clear, palegreenish-yellow, viscous “syrup”. The flask was then taken out of themantle, and the syrup was quickly blade-coated on a sheet of white kraftpaper with a glass rod at a coating level of about 10 mg/cm², to give athin, continuous, uniform layer of sticky, long-fiber-forming, “wet”coating. Subsequently, the paper coated with the adhesive layer wasplaced in an air-circulating oven maintained at 160° C. The heat causedthe cross-linking reaction of the coating composition. After 30 minutes,the coating became a clear, pale greenish-yellow, shiny, “dry” adhesivelayer of sufficient cohesion strength, although some blotches of no orlittle adhesive on the paper backing were noticeable probably due toretraction of the adhesive during polymerization and cross-linking. Thefinished PSA tape thus obtained possessed good initial tack, formed ropystructure upon removal of it from surfaces (e.g. metal, lacquer, glass,human skin) to which they are applied, and exhibited a good adhesivepower of about 3.2 lbf/inch on stainless steel (type 302). The 90° peeladhesion test method and conditions are described in Example 2; thesample tape was almost cleanly removed in the test, leaving only alittle adhesive residue on the panel.

Example 5

This example describes the preparation of a PSA composition from ESO andadipic acid in a molar ratio of 1.66:1 oxirane groups to carboxyl groupsand of PSA tapes comprising the composition. ESO (3.26 g, containingabout 14.3 mmol of oxirane groups) and adipic acid (0.63 g, containing8.6 mmol of carboxyl groups) were charged to a 50-mL, round-bottom flaskequipped with a heating mantle and a magnetic stirrer. The mixture washeated by a preheated mantle (180° C.) with stirring. After the mixtureturned clear and colorless, the heating was continued for another fourminutes at the same temperature to give a pale greenish-yellow, sort ofturbid, viscous “syrup”. The flask was then taken out of the mantle, andthe syrup was quickly blade-coated on a sheet of white kraft paper witha glass rod at a coating level of about 6.8 mg/cm², to give a thin,continuous, uniform layer of pale greenish yellow, sort of sticky,short-fiber-forming, “wet” coating. Subsequently, the paper coated withthe adhesive layer was placed in an air-circulating oven maintained at160° C. The heat caused the cross-linking reaction of the coatingcomposition. After 60 minutes, the coating became a clear, palegreenish-yellow, shiny, almost “dry” adhesive layer of fairly goodcohesion strength, although some patches of no or little adhesive on thepaper backing were noticeable probably due to retraction of the adhesiveduring polymerization and cross-linking. The finished PSA tape thusobtained possessed fairly good initial tack, formed ropy structure uponremoval of it from surfaces (e.g. metal, lacquer, glass, human skin) towhich they are applied, and exhibited an adhesive power of about 0.95lbf/inch on stainless steel (type 302). The 90° peel adhesion testmethod and conditions are described in Example 2; the sample tape wasalmost cleanly removed in the test, leaving a little adhesive residue onthe panel.

Example 6

This example describes the preparation of a PSA composition from ESO andadipic acid (in a molar ratio of 1:1 oxirane groups to carboxylic acidgroups) and of PSA foils comprising the composition. ESO (2.23 g,containing about 9.8 mmol of oxirane groups) and adipic acid (0.72 g,containing 9.8 mmol of carboxylic acid groups) were charged to a 50-mL,round-bottom flask equipped with a heating mantle and a magneticstirring. The mixture was heated by the preheated mantle (150° C.) withstirring. After the mixture turned clear and colorless, the heating wascontinued for another five minutes at the same temperature to give aclear, pale greenish-yellow, viscous “syrup”. The flask was then takenout of the mantle, and the syrup was quickly blade-coated on a sheet ofaluminum foil with a glass rod at a coating level of about 10 mg/cm², togive a thin, continuous, uniform layer of sticky, fiber-forming, “wet”coating. Subsequently, the foil coated with the adhesive layer wasplaced in an air-circulating oven maintained at 160° C. The heat causedthe cross-linking reaction of the coating composition. After 70 minutesin the oven, the coating became a clear, pale greenish-yellow, shiny,“dry” adhesive layer of sufficient cohesion strength, although a smallamount of blotches of no or little adhesive on the foil backing werestill noticeable probably due to retraction of the adhesive duringpolymerization and cross-linking. The finished PSA foil thus obtainedpossessed fairly good initial tack, formed ropy structure upon itsremoval from surfaces (e.g. metal, lacquer, glass, human skin) to whichthey are applied, and exhibited a good adhesive power of about 1.5lbf/inch on stainless steel (type 302). The 90° peel adhesion testmethod and conditions are described in Example 2; the sample tape wascleanly removed in the test, leaving no adhesive residue on the panel.

Example 7

This example describes the preparation of a PSA composition from ESO andsebacic acid (in a molar ratio of 1:1 oxirane groups to carboxylic acidgroups) and of PSA tapes comprising the composition. ESO (2.74 g,containing about 12.0 mmol of oxirane groups) and sebacic acid (1.22 gof containing 12.1 mmol of carboxylic acid groups) were charged to a50-mL, round-bottom flask equipped with a heating mantle and stirrerbar. The mixture was then heated by the preheated mantle (180° C.) withstirring. After the mixture became clear and colorless, the heating wascontinued for another four minutes at the same temperature to give aclear, pale greenish-yellow, viscous “syrup”. The flask was then takenout of the mantle, and the syrup was quickly blade-coated on a sheet ofwhite kraft paper with a glass rod at a coating level of about 8 mg/cm²,to give a thin, continuous, uniform layer of clear, sort of sticky,long-fiber-forming, “wet” coating. Subsequently, the paper coated withthe adhesive layer was placed in an air-circulating oven maintained at160° C. The heat caused the cross-linking reaction of the coatingcomposition. After 50 minutes in the oven, the coating became a clear,pale greenish-yellow, shiny, almost “dry” adhesive layer of sufficientcohesion strength, though leaving some blotches of no or little adhesiveon the paper backing (probably due to retraction of the adhesive duringpolymerization and cross-linking). The finished PSA tape thus obtainedpossessed good initial tack, formed ropy structure upon removal of itfrom surfaces (e.g. metal, lacquer, glass, human skin) to which they areapplied, and exhibited a good adhesive power of about 1.4 lbf/inch onstainless steel (type 302). The 90° peel adhesion test method andconditions are described in Example 2; the sample tape was almostcleanly removed in the test, leaving a little adhesive residue on thepanel.

Example 8

This example describes the preparation of a PSA composition from ESO andsuccinic acid in a molar ratio of 1:1 oxirane groups to carboxylic acidgroups and of PSA tapes comprising the composition. ESO (2.78 g,containing about 12.2 mmol of oxirane groups) and succinic acid (0.73 g,containing 12.4 mmol of carboxylic acid groups) were charged to a 50-mL,round-bottom flask equipped with a heating mantle and a magneticstirring. The mixture was heated up to 180° C. by the preheated mantlewith stirring, and heating was continued for five minutes at the sametemperature to give a clear, pale greenish-yellow, and viscous “syrup”.The flask was then taken out of the mantle, and the syrup was quicklyblade-coated on a sheet of white kraft paper with a glass rod at acoating level of about 8.6 mg/cm², to give a thin, continuous, uniformlayer of clear, pale greenish-yellow, sticky, fiber-forming and “wet”coating. Subsequently, the paper coated with the adhesive layer wasplaced in an air-circulating oven maintained at 160° C. The heat causedthe cross-linking reaction of the coating composition. After 20 minutesin the oven, the coating became a clear, pale greenish-yellow, shiny,“dry” adhesive layer of sufficient cohesion strength, although someblotches of no or little adhesive on the paper backing were noticeableprobably due to retraction of the adhesive during polymerization andcross-linking. The finished PSA tape thus obtained possessed goodinitial tack, formed ropy structure upon removal of it from surfaces(e.g. metal, lacquer, glass, human skin) to which they are applied, andexhibited a good adhesive power of about 2.3 lbf/inch on stainless steel(type 302). The 90° peel adhesion test method and conditions aredescribed in Example 2; the sample was cleanly removed in the test,leaving no adhesive residue on the panel.

Example 9

This example describes the preparation of a PSA composition from ESO andsuccinic acid in a molar ratio of 1:1.53 oxirane groups to carboxylicacid groups and of PSA tapes comprising the said composition. ESO (2.35g, containing about 10.3 mmol of oxirane groups) and succinic acid (0.93g, containing 15.8 mmol of carboxylic acid groups) were charged to a50-mL, round-bottom flask equipped with a heating mantle and a magneticstirring. The mixture was then heated by the preheated mantle (160° C.)with stirring, and heating was continued for six minutes at the sametemperature to give a clear, pale greenish-yellow and viscous “syrup”.The flask was then taken out of the mantle, and the syrup was quicklyblade-coated on a sheet of white kraft paper with a glass rod at acoating level of about 9 mg/cm², to give a thin, continuous, uniformlayer of clear, pale greenish yellow, sticky, fiber-forming, “wet”coating. Subsequently, the paper coated with the adhesive layer wasplaced in an air-circulating oven maintained at 160° C. The heat causedthe cross-linking reaction of the coating composition. After 25 minutesin the oven, the coating was converted into a clear, palegreenish-yellow, shiny, “dry” adhesive layer of sufficient cohesionstrength, although some blotches of no or little adhesive on the paperbacking were noticeable probably due to retraction of the adhesiveduring polymerization and cross-linking. The finished PSA tape thusobtained possessed good initial tack, formed ropy structure upon removalof it from surfaces (e.g. metal, lacquer, glass, human skin) to whichthey are applied, and exhibited a good adhesive power of about 2.1lbf/inch on stainless steel (type 302). The 90° peel adhesion testmethod and conditions are described in Example 2; the sample was cleanlyremoved in the test, leaving no adhesive residue on the panel.

Example 10

This example describes the preparation of a PSA composition from ESO andsuccinic acid (in a molar ratio of 1:1.05 oxirane groups to carboxylicacid groups), and of PSA tapes by transferring said PSA composition fromsiliconised release liner. ESO (2.53 g, containing about 11.1 mmol ofoxirane groups) and succinic acid (0.69 g, containing 11.7 mmol ofcarboxylic acid groups) were charged to a 50-mL, round-bottom flaskequipped with a heating mantle and a magnetic stirring. The mixture wasthen heated by the preheated mantle (180° C.) with stirring, and heatingwas continued for five minutes at the same temperature to give a clear,pale greenish-yellow and viscous “syrup”. The flask was then taken outof the mantle, and the syrup was quickly blade-coated on the siliconisedside of a sheet of siliconised paper with a glass rod at a coating levelof about 10 mg/cm², to give a thin, uniform layer of sticky,fiber-forming and “wet” coating. Subsequently, the adhesive coating wascovered with a sheet of kraft paper, resulting in a “sandwich” which wasthen pressed with a rubber roller to achieve sufficient wet-out of theadhesive onto the kraft paper backing in order to provide adequateadhesion and complete transfer of the adhesive. And then, thesiliconised paper was peeled off from the “sandwich”, with most of theadhesive transferring to the paper backing, but still leaving randompatches on the siliconised paper. Lastly, the paper backing coated withthe adhesive layer was placed in an air-circulating oven maintained at160° C. The heat caused the cross-linking reaction of the coatingcomposition. After 25 minutes in the oven, the coating was convertedinto a clear, pale greenish-yellow, shiny, and “dry” adhesive layer ofsufficient cohesion strength, but leaving some blotches of no or littleadhesive on the paper backing (probably due to retraction of theadhesive during polymerization and cross-linking). The finished PSA tapethus obtained possessed fairly good initial tack, formed ropy structureupon removal of it from surfaces (e.g. metal, lacquer, glass, humanskin) to which they are applied, and exhibited a good adhesive power ofabout 1.5 lbf/inch on stainless steel (type 302). The test method andconditions are described in Example 2; the sample tape was cleanlyremoved in the test, leaving no adhesive residue on the panel.

Example 11

This example describes the preparation of a PSA composition from ESO andadipic acid (in a molar ratio of 1:1.2 oxirane groups to carboxylic acidgroups) and of PSA tapes comprising the composition. ESO (4.03 g,containing about 17.6 mmol of oxirane groups) and 1.53 g of adipic acid(containing 20.9 mmol of carboxylic acid groups) were charged to a50-mL, round-bottom flask equipped with a heating mantle and a magneticstirring. The mixture was then heated by the preheated mantle (160° C.)with stirring, to give a clear, almost colorless, “syrup” of low tomedium viscosity. The flask was then taken out of the mantle, and thesyrup was quickly blade-coated on a sheet of white kraft paper with aglass rod at a coating level of about 8 mg/cm², to give a thin, layer ofnot fiber-forming, “waxy” coating. Subsequently, the paper coated withthe adhesive layer was placed in an air-circulating oven maintained at160° C. The heat caused the polymerization and the cross-linkingreaction of the coating composition. After 50 minutes in the oven, thecoating was converted into a clear, pale greenish-yellow, shiny, “dry”adhesive layer of fairly sufficient cohesion strength, but obviouslyleaving blotches of no or little adhesive on the paper backing (probablydue to retraction of the adhesive during polymerization andcross-linking). The finished PSA tape thus obtained possessed fairlygood initial tack, formed ropy structure upon removal of it fromsurfaces (e.g. metal, lacquer, glass, human skin) to which they areapplied.

Example 12

This example describes the preparation of a PSA composition from ESO andadipic acid in a molar ratio of 1:1.2 oxirane groups to carboxylic acidgroups with the aid of solvent p-xylene, and of PSA tapes comprising thecomposition. ESO (0.95 g, containing about 4.16 mmol of oxirane groups),adipic acid (0.36 g, containing 4.9 mmol of carboxylic acid groups) and0.39 g of p-xylene were charged to a 50-mL, round-bottom flask equippedwith a heating mantle and a magnetic stirring. The mixture was heated upto 130° C. by the preheated mantle with stirring. After the mixtureturned clear and colorless, heating was continued for another threeminutes at the same temperature to give a sort of turbid, palegreenish-yellow “syrup” of medium viscosity. The flask was then takenout of the mantle, and the syrup was quickly blade-coated on a sheet ofwhite kraft paper with a glass rod at a coating level of about 10mg/cm², to give a thin, continuous, uniform layer of clear, palegreenish yellow, sort of sticky, fiber-forming, “wet” coating.Subsequently, the paper coated with the adhesive layer was placed in anair-circulating oven maintained at 160° C. The heat caused thecross-linking reaction of the coating composition. After 30 minutes inthe oven, the coating was converted into a clear, pale greenish-yellow,shiny, “dry” adhesive layer of sufficient cohesion strength, but leavingsome small blotches of no or little adhesive on the paper backing(probably due to retraction of the adhesive during polymerization andcross-linking). The finished PSA tape thus obtained possessed fairlygood initial tack, formed ropy structure upon removal of it fromsurfaces (e.g. metal, lacquer, glass, human skin) to which they areapplied, and exhibited a good adhesive power of about 3.1 lbf/inch onstainless steel (type 302). The 90° peel adhesion test method andconditions are described in Example 2; the sample was almost cleanlyremoved in the test, leaving only a little adhesive residue on thepanel.

Example 13

This example describes the preparation of a PSA composition from ESO andadipic acid in a molar ratio of 1:1.2 oxirane groups to carboxylic acidgroups and of PSA tapes comprising the composition with the aid ofsiliconised release liner. ESO (7.89 g, containing about 34.5 mmol ofoxirane groups) and 3.03 g of adipic acid (containing 41.5 mmol ofcarboxylic acid groups) were charged to a 50-mL, round-bottom flaskequipped with a heating mantle and stirrer bar. The mixture was heatedby the preheated mantle (140° C.) with stirring. After the mixtureturned clear and colorless, heating was continued for another nineminutes at the same temperature to give a clear (slightly turbid), palegreenish-yellow, viscous “syrup”. The flask was then taken out of themantle, and the syrup was quickly blade-coated on the siliconised sideof a sheet of siliconised paper with a glass rod at a coating level ofabout 10 mg/cm², to give a thin, uniform layer of very sticky,fiber-forming and “wet” coating. Subsequently, the adhesive coating wasthen covered with a sheet of kraft paper, resulting in a “sandwich”which was then pressed with a rubber roller to achieve sufficientwet-out of the adhesive onto the kraft paper backing in order to provideadequate adhesion. Subsequently, the “sandwich” was placed in anair-circulating oven maintained at 160° C. The heat caused thecross-linking reaction of the coating composition. The “sandwich” waspressed again with the rubber roller after 20 minutes in the oven, andwas taken out of the oven after 10 more minutes in the oven. Thesiliconised paper was then peeled off with adhesive completelytransferred; and the coating on the paper backing was found to beconverted into a clear, pale greenish-yellow, shiny, uniform, “dry”adhesive layer of sufficient cohesion strength. The finished PSA tapethus obtained possessed good initial tack, formed ropy structure uponremoval of it from surfaces (e.g. metal, lacquer, glass, human skin) towhich they are applied, and exhibited a good adhesive power of about 3.2lbf/inch on stainless steel (type 302). The 90° peel adhesion testmethod and conditions are described in Example 2; the sample was almostcleanly removed in the test, leaving only a little adhesive residue onthe panel.

Example 14

This example describes the preparation of a PSA composition from ESO andadipic acid in a molar ratio of 1:1.2 oxirane groups to carboxylic acidgroups, and of polypropylene tapes comprising the composition with theaid of siliconised released liner. ESO (3.68 g, containing about 16.1mmol of oxirane groups) and adipic acid (1.45 g, containing 19.8 mmol ofcarboxylic acid groups) were charged to a 50-mL, round-bottom flaskequipped with a heating mantle and a magnetic stirring. The mixture washeated by the preheated mantle (140° C.) with stirring. After themixture turned clear and colorless, heating was continued for another4.5 minutes at the same temperature to give a clear (slightly turbid),pale greenish-yellow, viscous “syrup”. The flask was then taken out ofthe mantle, and the syrup was quickly blade-coated on the siliconisedside of a sheet of siliconised paper with a glass rod at a coating levelof about 10 mg/cm², to give a thin, uniform layer of very sticky,fiber-forming and “wet” coating. Subsequently, the adhesive coating wasthen covered with a sheet of PP film, resulting in a “sandwich” whichwas then pressed with a rubber roller to achieve sufficient wet-out ofthe adhesive onto the kraft paper backing in order to provide adequateadhesion. Subsequently, the “sandwich” was placed in an air-circulatingoven maintained at 130° C. The heat caused the cross-linking reaction ofthe coating composition. The “sandwich” was pressed again with therubber roller after 30 minutes in the oven, and was taken out of theoven after 120 more minutes in the oven. The siliconised paper was thenpeeled off with adhesive completely transferred; and the coating on thepolypropylene film was found to be converted into a clear, palegreenish-yellow, shiny, uniform/even, “dry” adhesive layer of sufficientcohesion strength. The finished PSA tape thus obtained possessed fairlygood initial tack, formed ropy structure upon removal of it fromsurfaces (e.g. metal, lacquer, glass, human skin) to which they areapplied, and exhibited a good adhesive power of about 2.2 lbf/inch onstainless steel (type 302). The 90° peel adhesion test method andconditions are described in Example 2; the sample was almost cleanlyremoved in the test, leaving little adhesive residue on the panel.

Example 15

This example describes the preparation of a PSA composition from ESO,adipic acid and lauric acid (oxirane groups/carboxylic acid groups molarratio, 1:1), and of PSA tapes comprising the composition. ESO (2.3 g,containing about 10.1 mmol of oxirane groups), adipic acid (0.6 g,containing 8.2 mmol of carboxylic acid groups) and lauric acid (0.4 g,containing 2.0 mmol of carboxylic acid groups) were charged to a 50-mL,round-bottom flask equipped with a heating mantle and a magneticstirring. The mixture was heated by the preheated mantle (160° C.) withstirring. After the mixture turned clear and colorless, the heating wascontinued for another 3.5 minutes at the same temperature to give aclear (sort of turbid), pale greenish-yellow, “syrup” of low to mediumviscosity. The flask was then taken out of the mantle, and the syrup wasquickly blade-coated on a sheet of white kraft paper with a glass rod ata coating level of about 7 mg/cm², to give a thin, continuous, uniformlayer of clear, pale greenish-yellow, sort of sticky,short-fiber-forming, “wet” coating. Subsequently, the paper coated withthe adhesive layer was placed in an air-circulating oven maintained at160° C. The heat caused the cross-linking reaction of the coatingcomposition. The coating was converted into a pale greenish-yellow,clear, shiny, “dry” adhesive layer of sufficient cohesion strength after90 minutes in the oven. However some small patches of no or littleadhesive on the paper backing were noticeable probably due to retractionof the adhesive during polymerization and cross-linking. The finishedPSA tape thus obtained possessed fairly good initial tack, formed ropystructure upon removal of it from surfaces (e.g. metal, lacquer, glass,human skin) to which they are applied, and exhibited a good adhesivepower of about 1.5 lbf/inch on stainless steel (type 302). The 90° peeladhesion test method and conditions are described in Example 2; thesample was almost cleanly removed in the test, leaving only a littleadhesive residue on the panel.

Example 16

This example describes the preparation of a PSA composition from ESO,adipic acid and lauric acid (oxirane group/carboxylic acid group molarratio, 1:1.14) in two steps, and of PSA tapes comprising thecomposition. ESO (6.32 g, containing about 27.7 mmol of oxirane groups)and lauric acid (1.28 g, containing 6.39 mmol of carboxylic acid groups)were charged to a 50-mL, round-bottom flask equipped with a heatingmantle and a magnetic stirring. The mixture was heated by the preheatedmantle (139° C.) with stirring, and the heating was continued for 75minutes at the same temperature to give a clear, yellow liquid of low tomedium viscosity. The temperature of mantle was then raised to 160° C.,and adipic acid (1.85 g, containing 25.3 mmol of carboxylic acid groups)was added slowly to the mixture while stirring. The flask was taken outof the mantle after eight more minutes, and the viscous syrup wasquickly blade-coated on a sheet of white kraft paper with a glass rod ata coating level of about 10 mg/cm², to give a thin, continuous, uniformlayer of clear, pale yellow, sort of sticky, short-fiber-forming, “wet”coating. Subsequently, the paper coated with the adhesive layer wasplaced in an air-circulating oven maintained at 160° C. The heat causedthe cross-linking reaction of the coating composition. The coating wasconverted into a clear, pale greenish-yellow, shiny, “dry” adhesivelayer of sufficient cohesion strength after 100 minutes in the oven.However, some small patches of no or little adhesive on the paperbacking were noticeable probably due to retraction of the adhesiveduring polymerization and cross-linking. The finished PSA tape thusobtained possessed fairly good initial tack, formed ropy structure uponremoval of it from surfaces (e.g. metal, lacquer, glass, human skin) towhich they are applied, and exhibited a good adhesive power of about 2.5lbf/inch on stainless steel (type 302). The 90° peel adhesion testmethod and conditions are described in Example 2; the sample was almostcleanly removed in the test, leaving only a little adhesive residue onthe panel.

Example 17

This example describes the preparation of a PSA composition from ESO,adipic acid and lauric acid (oxirane group/carboxylic acid group molarratio, 1:1.16) in two steps, and PSA tapes comprising the composition.ESO (6.38 g, containing about 27.9 mmol of oxirane groups) and aceticacid (0.48 g, containing 8.0 mmol of carboxyl groups) were charged to a50-mL, round-bottom flask equipped with a heating mantle and a magneticstirring. The mixture was heated by the preheated mantle (120° C.) withstirring, and the heating was continued for 90 minutes at the sametemperature to give a clear, yellow liquid of low to medium viscosity.The temperature of mantle was then raised to 160° C., and 1.78 g ofadipic acid (containing 24.4 mmol of carboxylic acid groups) was addedslowly to the mixture while stirring. The flask was taken out of themantle after ten more minutes, and the viscous syrup was quicklyblade-coated on a sheet of white kraft paper with a glass rod at acoating level of about 10 mg/cm², to give a thin, continuous, uniformlayer of clear, pale yellow, sort of sticky, short-fiber-forming, “wet”coating. Subsequently, the paper coated with the adhesive layer wasplaced in an air-circulating oven maintained at 160° C. The heat causedthe cross-linking reaction of the coating composition. The coating wasconverted into a clear, pale greenish-yellow, shiny, “dry” adhesivelayer of sufficient cohesion strength after 60 minutes in the oven,However, some small patches of no or little adhesive on the paperbacking were still noticeable probably due to retraction of the adhesiveduring polymerization and cross-linking. The finished PSA tape thusobtained possessed fairly good initial tack, formed ropy structure uponremoval of it from surfaces (e.g. metal, lacquer, glass, human skin) towhich they are applied, and exhibited a good adhesive power of about 2.3lbf/inch on stainless steel (type 302). The 90° peel adhesion testmethod and conditions are described in Example 2; the sample was almostcleanly removed in the test, leaving only a little adhesive residue onthe panel.

Example 18

This example describes the preparation of a PSA composition from ESO,adipic acid and lauric acid (oxirane group/carboxyl group molar ratio,1:1.14) in two steps, and the preparation of PSA tapes comprising thecomposition with the aid of siliconised released liner. ESO (4.53 g,containing about 19.8 mmol of oxirane groups) and acetic acid (0.35 g,containing 5.83 mmol of carboxylic acid groups) were charged to a 50-mL,round-bottom flask equipped with a heating mantle and a magneticstirring. The mixture was heated by the preheated mantle (120° C.) withstirring, and heating was continued for 160 minutes at the sametemperature to give a clear, yellow liquid of low to medium viscosity.The temperature of mantle was then raised to 130° C., and 1.23 g ofadipic acid (containing 16.8 mmol of carboxyl groups) was added slowlyto the mixture while stirring. The flask was then taken out of themantle after 13 more minutes, and the clear, viscous syrup was quicklyblade-coated on the siliconised side of a sheet of white kraft paperwith a glass rod at a coating level of about 7 mg/cm², to give a thin,continuous, uniform layer of clear, pale yellow, very sticky,fiber-forming, “wet” coating. Subsequently, the adhesive coating wasthen covered with a sheet of kraft paper, resulting in a “sandwich”which was then pressed with a rubber roller to achieve sufficientwet-out of the adhesive onto the kraft paper backing in order to provideadequate adhesion. Lastly, the “sandwich” was placed in anair-circulating oven maintained at 160° C. The heat caused thecross-linking reaction of the coating composition. The “sandwich” wastaken out of the oven after 60 minutes in the oven. The siliconisedpaper was peeled off with adhesive almost completely transferred; andthe coating on the paper backing was found to be converted into a clear,pale greenish-yellow, shiny, uniform, “dry” adhesive layer of sufficientcohesion strength. The finished PSA tape thus obtained possessed fairlygood initial tack, formed ropy structure upon removal of it fromsurfaces (e.g. metal, lacquer, glass, human skin) to which they areapplied, and exhibited a good adhesive power of about 2.5 lbf/inch onstainless steel (type 302). The 90° peel adhesion test method andconditions are described in Example 2; the sample was almost cleanlyremoved in the test, leaving a little adhesive residue on the panel.

Example 19

This example describes the preparation of a PSA composition from ESO andadipic acid in a molar ratio of 1:1.2 oxirane groups to carboxylic acidgroups, and of PSA tapes comprising the composition with the aid of twosiliconized release liners with different adhesion-repellence propertiesfor the adhesive composition. ESO (2.82 g, containing about 12.3 mmol ofoxirane groups) was charged to a 50-mL, round-bottom flask equipped witha silicon oil bath and magnetic stirring, and heated up to 135° C. bythe preheated oil bath with stirring, after which the resulting clearand colorless liquid was maintained at the same temperature. To theflask, 1.06 g of adipic acid (containing 14.5 mmol of carboxylic acidgroups) was then added over 3 minutes to give a clear (slightly turbid),almost colorless solution of low viscosity. Heating and stirring (600rpm) were continued for another 23 minutes at the same temperature togive a clear (slightly turbid), pale greenish-yellow, viscous “syrup”.When the magnetic stirring bar could not work smoothly above a stirringspeed of 200 rpm, the flask was then taken out of the oil bath, and thesyrup was quickly blade-coated on the siliconised face of a sheet ofpartially siliconized release liner with a glass rod at a coating levelof about 3 mg/cm², to give a thin, uniform layer of sticky,fiber-forming and “wet” coating layer. The adhesive layer was thencarefully covered (the siliconized face inwardly) with a sheet of fullysiliconized release liner with, resulting in a “sandwich” which was thenpressed with a rubber roller to achieve a good contact between theadhesive composition and the two liners. Subsequently, the “sandwich”was placed in an air-circulating oven maintained at 160° C. The heatcaused the cross-linking reaction of the coating composition. The“sandwich” was taken out of the oven after 30 minutes in the oven. Thefully siliconized released liner was quickly peeled off without takingaway any adhesive composition; a sheet of paper was immediately andcarefully covered on the adhesive layer. The new “sandwich” was thenpressed with a rubber roller to achieve sufficient wet-out of theadhesive onto the paper backing in order to provide adequate adhesion.After the “sandwich” was cooled down, the partially siliconized releaseliner could be easily peeled off with the adhesive composition beingcompletely transferred to the paper backing. The siliconized releaseliner can be optionally left for the protection of the adhesive layerson the paper backing or be recovered for re-use. The adhesive coating onthe paper backing was a thin, clear, pale greenish-yellow, shiny,uniform, “dry” adhesive layer of sufficient cohesion strength, and wasnot found to penetrate the paper backing to give an oily appearance ofthe PSA tape. The finished PSA tape thus obtained possessed good initialtack, formed ropy structure upon removal of it from surfaces (e.g.metal, lacquer, glass, human skin) to which they are applied, andexhibited a good adhesive power of about 2.8 lbf/inch on stainless steel(type 302). The 90° peel adhesion test method and conditions aredescribed in Example 2; the sample was cleanly removed in the test,leaving no adhesive residue on the panel.

Example 20

This example describes the preparation of a PSA composition from ESO andadipic acid in a molar ratio of 1:1.2 oxirane groups to carboxylic acidgroups in the presence of hexadecyltrimethyl ammonium bromide (1.0 wt %based on the weight of the reaction mixture), and of PSA tapescomprising the composition. ESO (2.36 g, containing about 10.3 mmol ofoxirane groups) was charged to a 50-mL, round-bottom flask equipped witha silicon oil bath and magnetic stirring, heated up to 135° C. by thepreheated oil bath with stirring, and the resulting clear and colorlessliquid was maintained at the same temperature. To the flask, 0.89 g ofadipic acid (containing 12.2 mmol of carboxylic acid groups) was thenadded portion-wise over 5 minutes to give a clear (slightly turbid),almost colorless solution of low viscosity. After five more minutes,0.033 g of hexadecyltrimethyl ammonium bromide was added to the reactionmixture. Heating and stirring (600 rpm) were thereupon continued foranother 18 minutes at the same temperature to give a clear (slightlyturbid), pale greenish-yellow, viscous “syrup” (at this point, themagnetic stirring bar could not work smoothly above a stirring speed of200 rpm). The flask was then taken out of the oil bath, and the syrupwas quickly blade-coated on a sheet of white paper with a glass rod at acoating level of about 6 mg/cm², to give a thin, continuous, uniformlayer of sticky, long-fiber-forming, “wet” coating. Subsequently, thepaper coated with the adhesive layer was placed in an air-circulatingoven maintained at 160° C. The heat caused the cross-linking reaction ofthe coating composition. The paper coated with the adhesive layer wastaken out of the oven after 6 minutes in the oven. The finished PSA tapehad a clear, pale greenish-yellow, shiny, “dry” adhesive layer ofsufficient cohesion strength, possessed good initial tack, formed ropystructure upon removal of it from surfaces (e.g. metal, lacquer, glass,human skin) to which they are applied, and exhibited a good adhesivepower of about 2.5 lbf/inch on stainless steel (type 302). The 90° peeladhesion test method and conditions are described in Example 2; thesample was cleanly removed in the test, leaving no adhesive residue onthe panel.

Example 21

This example describes the preparation of a PSA composition from ESO andadipic acid in a molar ratio of 1:1.2 oxirane groups to carboxylic acidgroups in the presence of triethanolamine (1.4 wt % based on the weightof the reaction mixture), and of PSA tapes comprising the composition.ESO (3.34 g, containing about 14.6 mmol of oxirane groups) was chargedto a 50-mL, round-bottom flask equipped with a silicon oil bath andmagnetic stirring, heated up to 135° C. by the preheated oil bath withstirring, and the resulting clear and colorless liquid was maintained atthe same temperature. To the flask, 1.28 g of adipic acid (containing17.5 mmol of carboxylic acid groups) was then added over 3 minutes togive a clear (slightly turbid), almost colorless solution of lowviscosity. After five more minutes, 0.065 g of triethanolamine was addedto the reaction mixture. Heating and stirring (600 rpm) were thereuponcontinued for another 10 minutes at the same temperature to give a clear(slightly turbid), pale orange-yellow, viscous “syrup” (at this point,the magnetic stirring bar could not work smoothly above a stirring speedof 200 rpm). The flask was then taken out of the oil bath, and the syrupwas quickly blade-coated on a sheet of white paper with a glass rod at acoating level of about 6 mg/cm², to give a thin, continuous, uniformlayer of sticky, long-fiber-forming, “wet” coating. Subsequently, thepaper coated with the adhesive layer was placed in an air-circulatingoven maintained at 160° C. The heat caused the cross-linking reaction ofthe coating composition. The paper coated with the adhesive layer wastaken out of the oven after 4 minutes in the oven. The finished PSA tapehad a clear, pale yellow, shiny, “dry” adhesive layer of sufficientcohesion strength, possessed good initial tack, formed ropy structureupon removal of it from surfaces (e.g. metal, lacquer, glass, humanskin) to which they are applied, and exhibited a good adhesive power ofabout 2.6 lbf/inch on stainless steel (type 302). The 90° peel adhesiontest method and conditions are described in Example 2; the sample wascleanly removed in the test, leaving no adhesive residue on the panel.

Example 22

This example describes the preparation of a PSA composition from ESO andadipic acid in a molar ratio of 1:1.2 oxirane groups to carboxylic acidgroups in the presence of chromium (III) tris(acetylacetonate) (0.2 wt %based on the weight of the reaction mixture), and of PSA tapescomprising the composition. ESO (2.66 g, containing about 11.6 mmol ofoxirane groups) was charged to a 50-mL, round-bottom flask equipped witha silicon oil bath and magnetic stirring, heated up to 135° C. by thepreheated oil bath with stirring, and the resulting clear and colorlessliquid was maintained at the same temperature. To the flask, 1.00 g ofadipic acid (containing 13.9 mmol of carboxylic acid groups) was thenadded over 3 minutes to give a clear (slightly turbid), almost colorlesssolution of low viscosity. After four more minutes, 0.007 g of chromium(III) tris(acetylacetonate) was added to the reaction mixture. Heatingand stirring (600 rpm) were thereupon continued for another 8 minutes atthe same temperature to give a clear (slightly turbid), paleolive-yellow, viscous “syrup” (at this point, the magnetic stirring barcould not work smoothly above a stirring speed of 200 rpm). The flaskwas then taken out of the oil bath, and the syrup was quicklyblade-coated on a sheet of white paper with a glass rod at a coatinglevel of about 6 mg/cm², to give a thin, continuous, uniform layer ofsticky, long-fiber-forming, “wet” coating. Subsequently, the papercoated with the adhesive layer was placed in an air-circulating ovenmaintained at 160° C. The heat caused the cross-linking reaction of thecoating composition. The paper coated with the adhesive layer was takenout of the oven after 4 minutes in the oven. The finished PSA tape had aclear, pale yellow, shiny, “dry” adhesive layer of sufficient cohesionstrength, possessed good initial tack, formed ropy structure uponremoval of it from surfaces (e.g. metal, lacquer, glass, human skin) towhich they are applied, and exhibited a good adhesive power of about 2.6lbf/inch on stainless steel (type 302). The 90° peel adhesion testmethod and conditions are described in Example 2; the sample was cleanlyremoved in the test, leaving no adhesive residue on the panel.

In view of the many possible embodiments to which the principles of thedisclosed compositions, articles of manufacture, and processes may beapplied, it should be recognized that the illustrated embodiments areonly preferred examples of the invention and should not be taken aslimiting the scope of the invention.

What is claimed is:
 1. A pressure sensitive adhesive composition made bya method comprising: initially reacting an epoxidized vegetable oil withat least one dibasic acid or anhydride thereof to produce a prepolymerproduct, wherein the amount of dibasic acid or anhydride reacted withthe epoxidized vegetable oil is sufficient to provide a 5 to 80 mol %excess of carboxylic acid groups over that required to esterify all theepoxy groups present in the at least one epoxidized vegetable oil; andfurther reacting the prepolymer product to produce the pressuresensitive adhesive composition.
 2. The composition of claim 1, whereinthe epoxidized vegetable oil is epoxidized soybean oil.
 3. Thecomposition of claim 2, wherein the dibasic acid or anhydride isselected from malonic acid, succinic acid, glutaric acid, adipic acid,pimelic acid, suberic acid, azelaic acid, sebacic acid, brassylic acid,succinic anhydride, or a mixture thereof.
 4. The composition of claim 2,wherein the dibasic acid or anhydride is an aliphatic saturatedcarboxylic dibasic acid or anhydride.
 5. The composition of claim 1,wherein the dibasic acid or anhydride is a dicarboxylic acid oranhydride thereof.
 6. The composition of claim 1, wherein the dibasicacid or anhydride is selected from malonic acid, succinic acid, glutaricacid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacicacid, brassylic acid, succinic anhydride, or a mixture thereof.
 7. Thecomposition of claim 1, wherein the vegetable oil and dibasic acid oranhydride are all from renewable sources.
 8. The composition of claim 1,wherein the epoxidized vegetable oil has an epoxy number of 2 to
 5. 9.The composition of claim 1, wherein the dibasic acid or anhydride is analiphatic saturated carboxylic dibasic acid or anhydride.
 10. Thecomposition of claim 1, wherein initially reacting the epoxidizedvegetable oil with at least one dibasic acid or anhydride thereofcomprises heating a mixture of the epoxidized vegetable oil and at leastone dibasic acid or anhydride at a temperature of 80 to 300° C.
 11. Thecomposition of claim 1, wherein the further reacting of the prepolymerproduct comprises heating the prepolymer product at a temperature of 100to 300° C.